<?php
function getDirContents($dir, &$results = array()) {
    $files = scandir($dir);

    foreach ($files as $key => $value) {
        $path = $dir . DIRECTORY_SEPARATOR . $value;
        if (!is_dir($path)) {
            $results[] = $path;
        } else if ($value != "." && $value != "..") {
            getDirContents($path, $results);
            $results[] = $path;
        }
    }

    return $results;
}

$filetree = array();

foreach(getDirContents('./js') as $path)
{
    $split = explode(DIRECTORY_SEPARATOR, $path);
    $last = $split[count($split) - 1];
    $fileOrDir = explode('.', $last);

    $var_ref =& $filetree;
    foreach ($split as $path_item)
    {
        $var_ref =& $var_ref[$path_item];
    }
}

echo '<pre>';
print_r($filetree);
echo '</pre>';